Harold White Jr. left his vehicle parked in front of a downtown building on Fourth Avenue at 10 p.m. Tuesday and called a friend to pick it up, police said.

"Family members described this behavior as highly unusual, and White hasn't been seen or heard from since," police said in a written statement. "White has been diagnosed with medical conditions and does not have his medication."

White, 47, is described as white, about 5 feet 11 inches and 170 pounds, with brown hair that's partially gray, and he was last seen wearing a black T-shirt and dark blue jeans.

He's known to frequent the South Side, Oakland and Bellevue areas on foot, police said.

Anyone who has seen White is asked to call 911 or the city's missing persons office at 412-323-7800.